The National Bladder Cancer Project, a national program of research with headquarters at the St. Vincent Hospital in Worcester, Massachusetts, supports qualified investigators through grants from the National Cancer Institute in those areas which have been designated as high priority for immediate implementation by experts in the various disciplines experienced in bladder cancer research. The ultimate objective of the Program is the elimination of morbidity and mortality from bladder cancer. Ideally this would be achieved by prevention, which would follow identification and avoidance of the causative agent(s) or by mitigating the effect of the causative agent(s) on the subject. In lieu of prevention, successful therapy becomes the intermediate goal. Classification of patients for treatment becomes one of the principal aims of diagnosis. Further, clinical and basic scientists believe that, because some of the etiologic factors in human bladder cancer have already been identified, research focused on some of the known, or strongly suspected agents, might permit an ability to break the pathogenic chain of events leading to bladder cancer, thus preventing its development. Such studies also offer unique opportunities for obtaining informatiion on broader questions of environmental carcinogenesis and tumor-host interactions--including immunologic aspects of host resistance.